KR0164041B1 - Heat sensitive recording material - Google Patents

Abstract

The thermally sensitive recording material for thermal recording paper comprising a developer, a coloring agent and a sensitizer and coated on a support, wherein the benzoin derivative represented by the following general formula (I) is used as a sensitizer. A thermal recording material comprising:

(Wherein n represents an integer value of 1 or 2, X and Y may be the same or different, and each is a hydrogen atom, a halogen atom, a nitro group, an acyl group, an aryl group, an aryloxy group, C ₁ to C Mono- or tri-substituted with ₁₀ or more linear or branched alkyl groups or alkyloxy groups.)

The thermal recording material provided by the present invention improves the generation sensitivity of the thermal recording paper and the storage stability of the uncolored and colored layers without deterioration of whiteness, without the problem of grease bleeding, and further, the color concentration for applied energy is excellent. .

Description

Thermal recording material

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording material, and more particularly, to a thermal recording material having high color sensitivity and excellent stability of an uncolored layer and a color developing layer.

More specifically, the present invention is a thermally sensitive recording material mainly composed of a color developer, a developer, and a sensitizer. Since the benzoin-based derivative is used as a sensitizer, it has high sensitivity and excellent stability of the uncolored layer and the color layer. A thermal recording material for thermal recording paper.

Thermal recording papers are known in which color developments are performed by contacting both color development materials by heat using color development reactions of colorless to pale basic dyes with a developer.

Background Art [0002] Conventionally, as a support for such thermal recording paper, paper is mainly used due to the inexpensive value, the simplicity of the recording device, the ease of use thereof, and the like. The thermal facsimile machine, thermal printer, POS label system, and other various measuring instruments are mainly used. It is widely used as a recording medium.

In recent years, with the continuous improvement of various thermal recording media such as thermal fax machines, thermal printers, and label systems using such thermal recording paper, remarkable speed-up of the heating recording system has been promoted. Along with the high speed in the field of thermal recording media, there has been a strong demand for improvement of the recording sensitivity of thermal recording paper used in such a medium, and many proposals have been made.

In general, the color-coating layer coating solution of thermal recording paper is composed of a lactone-based compound that forms color as a color developing agent and an acidic substance causing color development as a color developing agent.

In addition, in the color development of thermal recording paper, the paper used as a support may be kept at a temperature of 140-150 占 폚 to obtain excellent color.

For example, Japanese Patent Publication No. 45-14039 coats a coloring compound (or coloring agent) and an acidic substance (or coloring agent) such as an organic acid or a phenolic compound on a support or a base material, and generates both colors by heat. A thermal recording paper is disclosed in which a color is obtained by contacting a substance.

However, when such a thermal recording paper is used in a thermal head printer, not only the color development sensitivity is sufficiently exhibited but also the problem of lowering the greeting speed arises.

In addition, Japanese Patent Application Laid-Open No. 54-74762 has a thermal recording paper coated with a coloring agent and an acidic substance such as benzyl P-hydroxybenzoate on a support or a base paper to bring both coloring materials into contact with heat to obtain a color. Is disclosed.

However, when such thermal recording paper is used in a thermal head printer, not only the color sensitivity is sufficiently exhibited, but also there is a problem in the storage properties of the uncolored layer and the color layer.

On the other hand, in order to solve the problems as described above, in order to quickly and easily obtain a good image in the color-coating layer coating solution mainly composed of a color developer and a developer, an additive (or a sensitizer; hereinafter referred to as a sensitizer) is further added. There is a method of adding, and sensitizers used for this purpose are known to exhibit sufficiently high color sensitivity with little energy.

For example, Japanese Patent Laid-Open No. 48-1923 discloses a method of using waxes as such sensitizers.

However, in the case of using waxes as sensitizers in this way, the compatibility with organic acids is limited, which is not only unsatisfactory in their use and effects, but also due to the non-tackiness of the waxes, mold release, etc. Problems such as poor quality.

Also, Japanese Patent Publication No. 51-27599 discloses a method of using fatty acid anilide as such a sensitizer.

However, in such a case, as in the case of using waxes, problems of personnel bleeding are caused.

In addition, Japanese Patent Publication No. 43-4160 discloses a method of using acetanilides as a sensitizer.

However, when such acetanilides are used as a sensitizer, the thermal recording paper obtained by coating a chromophoric layer coating liquid containing the same on the support due to the sublimability of acetanilide itself is poor in terms of storage stability of the formed image. In addition, there are still problems such as poor whiteness and less gradient of color concentration with respect to applied temperature during color development.

In addition, Japanese Patent Application Laid-Open No. 54-139740 discloses a method of using stearamides as sensitizers.

However, in such a case, there is a problem such as poor color sensitivity and poor stability of the color layer.

Recently, in order to solve the problems of the prior art, a melting point of 80-120 ° C. is commonly used among compounds having a chemical structure composed of ether bonds or ester bonds such as aralkyl groups, phenyl groups, biphenyl groups, naphthyl groups, or alkyl groups. There is an active research for selecting compounds having sex and using them as sensitizers.

However, although thermal recording papers obtained using such ether- or ester-type compounds as sensitizers exhibit improved color sensitivity, there are still problems in storage and stability.

Accordingly, the present inventors conducted various experiments in order to provide a thermal recording material having high color sensitivity and excellent storage stability of the uncolored layer and the colored layer. As a result, esters or ethers, which have not been conventionally used as sensitizers at all, The present invention has been completed by using a ketone form of a compound in which the α-position of the benzoin compound, but not the form, is newly used as a sensitizer.

That is, the present invention has been made to solve the problems of the prior art as described above, the object of the present invention is to improve the color sensitivity of the thermal recording paper and the storage stability of the uncolored layer and the color layer without deterioration of whiteness In addition, the present invention provides a thermal recording material for thermal recording paper which has no problem of personnel bleeding and is excellent in color development concentration for applied energy.

In order to achieve the above object, the present invention is to use a benzoin derivative represented by the following general formula (I) as a sensitizer in a thermal recording material for thermal recording paper coated on a support or a base paper. A thermal recording material for thermal recording paper is provided. :

(Wherein n represents an integer value of 1 or 2, X and Y may be the same or different, and each is a hydrogen atom, a halogen atom, a nitro group, an acyl group, an aryl group, an aryloxy group, C ₁ to C _A mono- or tri-substituted ₁₀ -membered straight or branched chain alkyl group or an alkyloxy group).

In the present invention, as the colorless to pale basic dye (or coloring agent) component constituting the coloring layer, triphenylmethane-based, triarylmethane-based, lactone-based, or fluorane-based dyes can be used, and preferably fluorane Type leuco dyes can be used. Such a leuco dye is a colorless or pale dye used for thermal recording paper, which reacts with a developer in the presence of thermal energy to exhibit color.

In addition, in the present invention, the colorant component used in combination with the above-described coloring agent has a property of liquefying, vaporizing or dissolving with an increase in temperature, and having a characteristic of developing in contact with the above-described coloring agent. Any color developer can also be used.

Among the above-described coloring agents and developing agents, in particular, in the present invention, 3-diethylamino-7- (0-fluoroanilino) fluorane or the like is used, and as the developing agent, bisphenol A, or 2, Preference is given to using 2-bis (4-hydroxyphenyl) pentane or the like.

The mixing ratio of the above-described color developer and the developer is usually 100-1000 parts by weight of the developer based on 100 parts by weight of the color developer.

In addition, all the above-mentioned coloring agents or developing agents can also be used in mixture of 2 or more types as needed.

On the other hand, in the present invention, as a sensitizer which improves the preservability and makes the recordability excellent while increasing the color sensitivity to dyes compared with the case of using a conventionally known sensitizer, the above-described general formula (I) By using a benzoin derivative, a thermal recording material having a high color sensitivity and excellent storage stability of the uncolored layer and the color layer is provided.

That is, as the sensitizer (or 'heat-soluble material') usable in the present invention, in particular, the benzo represented by the general formula (I) having a melting point of 70 ° C. or higher, preferably 70 ° C. to 120 ° C., in the thermal recording layer. Phosphorus derivatives are preferred, and such sensitizers exhibit good color development.

Specific examples of such heat-soluble materials include the following compounds:

The heat-soluble material by this invention can be used individually or in mixture of 2 or more types within the range which does not inhibit the effect required by this invention.

Such heat-soluble material is preferably added in an amount of 100 to 350% by weight based on the basic dye used. If the amount of the heat-soluble substance exceeds 350% by weight, the usability of the entire reaction mixture system is poor, and when the amount of the heat-soluble substance is less than 100% by weight, the color sensitivity of the thermal recording paper decreases. do.

In the thermal recording material according to the present invention, the reason why the heat-soluble material represented by the general formula (I) used as a sensitizer improves the recording sensitivity without reducing the whiteness is due to the chemical structure of the benzoin derivative (I). This is because is similar to the structure of the basic dye and the organic developer, resulting in improved compatibility of the entire reaction mixture system.

Such benzoin derivatives may be synthesized in a laboratory or laboratory by methods commonly known in the art, or purchased and purified from commercially available products.

In the present invention, in the preparation of the thermal recording material containing the above-described chromophoric layer components, water is used as a dispersion medium, an appropriate dispersant is selected, and a solid grinder such as a ball mill or a sand grinder is used to The thermal recording material for thermal recording paper according to the present invention is produced by grinding and dispersing until the particle diameter becomes 10 microns or less.

In the present invention, zinc stearate can be further added to the thermal recording material as a running property improving agent in order to smooth the lubricating action between the thermal head and the compound as necessary.

On the other hand, in the thermal recording paper obtained by coating the thermal recording material according to the present invention on a support, the formation of the recording layer is not limited to a particular method, but can be performed according to the conventionally known techniques. For example, as a method of coating the thermal recording material on the support, an appropriate coating method such as an air knife coating method, a blade coating method, or a wire bar can be used.

Further, no coating amount is specifically limited to the heat-sensitive recording paper of the heat-sensitive recording material, the original surface of the generally basic weight 50g / m ² by dry weight can be coated in the range of 2 to 15g / m ^2.

Further, the support for use in coating the thermal recording material according to the present invention is not particularly limited. For example, paper, synthetic fiber paper, synthetic resin film, or the like can be used.

In particular, an overcoat layer or an undercoat layer may be provided above or below the coloring layer for the purpose of protecting the coloring layer.

The thermal recording paper obtained by coating the thermal recording material of the present invention having the above structure has high color development without deterioration of whiteness.

That is, in the present invention, a benzoin derivative of ketone, which is not known in the art, is used as a sensitizer to be added to the chromophoric layer thermal recording material in a thermal recording paper produced by coating a chromophoric layer heating recording material on a support or a base paper. This results in a much higher color sensitivity to the applied energy than when only bisphenol crab developers, fluorane colorants, or the like are used as sensitizers or stearamide (or stearate amide) compounds. In addition, there is no problem of grease smearing, and moreover, it is possible to manufacture high-sensitivity thermal recording paper having excellent whiteness and storage stability.

Next, a preferred embodiment of the present invention is described.

However, these examples are provided only to illustrate the present invention in more detail, the scope of the present invention is not limited only to these examples. In addition, all the parts used in the following Example and a comparative example mean a weight part.

Example 1

(A liquid: color developer included)

3-diethylamino-6-methyl-7-anilinofluorane (coloring agent). . . . . . . ... chapter 1,

Deoxy-4'-methylbenzoin (sensitizer; melting point: 96 ° C). . . . . . . . . . . . . . . . . . 2.0,

13% polyvinyl alcohol (PVA) aqueous solution (dispersant) of polymerization degree 100-170. . . . 3.0,

Pure water (H ₂ O). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.0 parts,

(B amount: With developer)

Bisphenol A (Developer). . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . 3.0,

1, 1, 3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane. . . ... 1.5,

Calcium Carbonate (CaCO ₃ ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0,

13% polyvinyl alcohol aqueous solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0,

Zinc stearate (travelling enhancer). . . . . . . . . . . ... . . . . . . . . . . 0.5 part,

pure. . . . . . . . . ... . . . . ... . . ... . . . . . . . . . . . . . . . . . Part 10.0,

After preparing the liquid A and liquid B of the composition liquid as described above, the average particle diameter of the solid content in the ball mill was pulverized to 10 μm or less, and the liquid A and the liquid B thus treated were mixed in a weight ratio of 1: 1. Then, it was dispersed for about 5 minutes to prepare a thermal recording material for thermal recording paper according to the present invention.

Example 2

Treatment was carried out in substantially the same manner as in Example 1, except that dioxy-4-methylbenzoin (melting point: 108 ° C.) was used in place of the sensitizer, dioxy-4′-methylbenzoin. A thermal recording material was prepared.

Example 3

Substantially the same method as in Example 1, except that dioxy-4,4'-dimethylbenzoin (melting point: 101 ° C) was used in place of the sensitizing agent, dioxy-4'-methylbenzoin. The thermal recording material was prepared by treating with.

Example 4

Except for the use of deoxynizoin (melting point: 110-112 ° C.) in place of the sensitizer deoxy-4′-methylbenzoin in the solution A, thermal treatment was performed in the same manner as in Example 1 above. The material was prepared.

Example 5

Substantially the same method as in Example 1, except that dioxy-4-methoxybenzoin (melting point: 76 ° C to 78 ° C) was used instead of the sensitizer dioxy-4'-methylbenzoin in the solution A. The thermal recording material was prepared by treating with.

Example 6

In the same manner as in Example 1 except that dioxy-4-chlorobenzoin (melting point: 103 to 105 ° C) was used instead of the sensitizer dioxy-4'-methylbenzoin in the solution A. The thermal recording material was prepared by treatment.

Example 7

Substantially the same method as in Example 1, except that dioxy-4-bromobenzoin (melting point: 109-112 ° C.) was used in place of the sensitizer, dioxy-4′-methylbenzoin. The thermal recording material was prepared by treating with.

Comparative Example 1

A thermally sensitive recording material was prepared in the same manner as in Example 1 except that stearic acid amide was added in the same amount as the sensitizer in place of the sensitizer dioxy-4'-methylbenzoin.

Comparative Example 2

A thermally sensitive recording material was prepared in the same manner as in Example 1 except that dioxy-4'-methylbenzoin was not added in the solution A.

In order to examine the thermal characteristics of the thermal recording materials obtained in Examples 1 to 7 and Comparative Examples 1 and 2, a wire bar was used so that the coating amount was 5 g / m ^{2 on} a paper having a basis weight of 50 g / m ^2. After coating and drying, it was processed to a smoothness of 200 to 800 seconds with a supercalendar to prepare a thermal recording paper, and the color concentration and the whiteness of the recording paper were measured and shown in Table 1 below.

In addition, heat resistance and light resistance were measured as a measure of image retention of the thermal recording paper thus obtained, and are shown in Table 2 below.

As can be seen from the results of Table 1 and Table 2, the thermal recording paper obtained by coating the thermal recording material according to the present invention is manufactured without using a thermal recording paper or a sensitizer manufactured using a conventional sensitizer. Compared with the thermal recording paper, it can be seen that it exhibits high sensitivity without the whiteness of the basement and exhibits improved image retention.

Claims (2)

A thermal recording material for thermal recording paper comprising a color developer, a developer, and a sensitizer, wherein the benzoin derivative represented by the following general formula (I) is used as the sensitizer. Thermal recording material:

(Wherein n represents an integer value of 1 or 2, X and Y may be the same or different, and each is a hydrogen atom, a halogen atom, a nitro group, an acyl group, an aryl group, an aryloxy group, C ₁ to C Mono- or tri-substituted with ₁₀ or more linear or branched alkyl groups or alkyloxy groups.) The thermally sensitive recording material according to claim 1, wherein the sensitizer is added in an amount of 100 to 350% by weight based on the base dye.